Re-epithelialization wound dressings and systems

ABSTRACT

Methods, apparatuses, and systems for promoting re-epithelialization as an aspect of wound healing are presented. A re-epithelialization dressing for use with reduced pressure has a moist tissue-interface layer, a manifold member, and a sealing member. The moist tissue-interface layer has a plurality of apertures. The moist tissue-interface layer is for disposing adjacent to the wound and provides a moisture balance (i.e., provides moisture when the wound is dry and receives moisture when the wound site is substantially wet). The reduced pressure, apertures, and moist tissue-interface layer help with liquid management and otherwise promote re-epithelialization. Other systems, apparatuses, and methods are presented.

RELATED APPLICATION

The present invention claims the benefit, under 35 USC §119(e), of thefiling of U.S. Provisional Patent Application Ser. No. 61/237,486entitled “Re-Epithelialization Wound Dressings and Systems,” filed Aug.27, 2009, which is incorporated herein by reference for all purposes.

BACKGROUND

The present disclosure relates generally to medical treatment systemsand, more particularly but not by way of limitation, tore-epithelialization wound dressings and systems.

The physiological process of wound healing involves different phasesthat may occur simultaneously or sequentially. As used herein, “or” doesnot require mutual exclusivity. Two phases of the wound healing processinvolve granulation (proliferation) and re-epthiliazation.

SUMMARY

Improvements to certain aspects of wound care dressings, methods, andsystems are addressed by the present invention as shown and described ina variety of illustrative, non-limiting embodiments herein. According toan illustrative, non-limiting embodiment, a re-epithelializationdressing for use with reduced pressure includes a moist tissue-interfacelayer, a manifold member, and a sealing member. The moisttissue-interface layer is adapted to provide a moisture balance for thetissue and is formed with a plurality of apertures. The manifold isoperable to distribute reduced pressure and is disposed between thesealing member and the moist tissue-interface layer.

According to another illustrative, non-limiting embodiment, a system forpromoting re-epithelialization of a wound includes are-epithelialization wound dressing. The re-epithelialization wounddressing includes a moist tissue-interface layer, a manifold member, anda sealing member. The moist tissue-interface layer is adapted to providea moisture balance for the tissue and is formed with a plurality ofapertures. The manifold is operable to distribute reduced pressure andis disposed between the sealing member and the moist tissue-interfacelayer. The system further includes a reduced-pressure connector, areduced-pressure delivery conduit, and a reduced-pressure source toprovide reduced pressure to the re-epithelialization wound dressing. Thereduced-pressure delivery conduit is operable to fluidly couple thereduced-pressure source to the reduced-pressure connector.

According to another illustrative, non-limiting embodiment, a method forpromoting re-epithelialization of a wound includes the steps of:deploying a re-epithelialization dressing proximate the wound; fluidlycoupling a reduced-pressure delivery conduit to the re-epithelializationdressing; and providing reduced pressure to the reduced-pressuredelivery conduit. The re-epithelialization dressing includes a moisttissue-interface layer operable to provide a moisture balance. The moisttissue-interface layer has a first side and a second, tissue-facing sideand is formed with a plurality of apertures. The re-epithelializationdressing further includes a manifold member for distributing reducedpressure. The manifold member has a first side and a second,tissue-facing side. The re-epithelialization dressing also includes asealing member, which has a first side and a second, tissue-facing side.The manifold member is disposed between the sealing member and the moisttissue-interface layer.

Other features and advantages of the illustrative embodiments willbecome apparent with reference to the drawings and detailed descriptionthat follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram with a portion in cross section of anillustrative, non-limiting embodiment of a system for treating a wound;

FIG. 2 is a schematic detail of a portion of the illustrative,non-limiting embodiment of a system for treating a wound of FIG. 1 shownwithout reduced pressure applied;

FIG. 3 is a schematic detail of a portion of the illustrative,non-limiting embodiment of a system for treating a wound of FIG. 1 shownwith reduced pressure applied; and

FIG. 4 is a schematic detail of a portion of the illustrative,non-limiting embodiment of a system for treating a wound of FIG. 1 shownwith an, absorber layer added.

DETAILED DESCRIPTION

In the following detailed description of the illustrative, non-limitingembodiments, reference is made to the accompanying drawings that form apart hereof. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it isunderstood that other embodiments may be utilized and that logicalstructural, mechanical, electrical, and chemical changes may be madewithout departing from the spirit or scope of the invention. To avoiddetail not necessary to enable those skilled in the art to practice theembodiments described herein, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the illustrative embodiments are defined only by the appendedclaims.

Referring primarily to FIG. 1, an illustrative, non-limiting embodimentof a wound treatment system 100, which includes a re-epithelializationdressing 102, is presented. The re-epithelialization dressing 102 isshown deployed for treatment on a tissue site 104 and in particular awound 106, or wound site. The wound 106 is shown extending throughepidermis 108 and into subcutaneous tissue 110. The tissue site 104 maybe the bodily tissue of any human, animal, or other organism, includingbone tissue, adipose tissue, muscle tissue, dermal tissue, vasculartissue, connective tissue, cartilage, tendons, ligaments, or any othertissue. The wound treatment system 100 with the re-epithelializationdressing 102 promotes re-epithelialization of the wound 106 and mayencourage migration of wound edges 112.

The re-epithelialization, or epithelialization, phase of acute woundhealing involves resurfacing of the wound 106 and changes in the woundedges 112. The process protects a patient's body from invasion byoutside organisms and may occur concurrently with other phases if notrestricted. The resurfacing aspect involves keratinocytes.

Among other things, keratinocytes form layers of the dermis andepidermis. Keratinocytes are derived from epidermal stem cells locatedin the bulge area of hair follicles and migrate from that location intothe basal layers of epidermis. The keratinocytes proliferate anddifferentiate to produce epidermis and thereby replenish the epidermis.Keratinocytes may respond to signals released from growth factors, whichmay be in wound exudate, by advancing in a sheet to resurface a space.Because of this migration, a moist wound environment may speed orotherwise facilitate the migration of keratinocytes toward one anotherfrom the wound edges 112. The wound treatment system 100 promotes thisre-epithelialization phase or process.

The wound treatment system 100 includes a reduced-pressure connector 114that may be associated with the re-epithelialization dressing 102 forproviding reduced pressure to at least a portion of there-epithelialization dressing 102. A reduced-pressure delivery conduit116 may be fluidly coupled to the reduced-pressure connector 114 at afirst end 118 and fluidly coupled to a reduced-pressure source 120 at asecond end 122. One or more devices 124 may be fluidly coupled betweenthe reduced-pressure connector 114 and the reduced-pressure source 120,such as on the reduced-pressure delivery conduit 116.

The device or devices 124 that may be fluidly coupled to thereduced-pressure delivery conduit 116 include, for example, withoutlimitation, a fluid reservoir (or collection member, to hold exudatesand other fluids removed), a pressure-feedback device, a volumedetection system, a blood detection system, an infection detectionsystem, a flow monitoring system, a temperature monitoring system, orother device.

The reduced-pressure source 120 provides reduced pressure as a part ofthe wound treatment system 100. The term “reduced pressure” as usedherein generally refers to a pressure less than the ambient pressure atthe tissue site 104 that is being subjected to treatment. In most cases,this reduced pressure will be less than the atmospheric pressure atwhich the patient is located. Alternatively, the reduced pressure may beless than a hydrostatic pressure of tissue at the tissue site 104.Although the terms “vacuum” and “negative pressure” may be used todescribe the pressure applied to the tissue site, the actual pressureapplied to the tissue site may be significantly more than the pressurenormally associated with a complete vacuum. Unless otherwise indicated,values of pressure stated herein are gauge pressures.

The reduced pressure delivered by the reduced-pressure source 120 may beconstant or varied (patterned or random) and may be deliveredcontinuously or intermittently. In order to maximize patient mobilityand ease, the reduced-pressure source 120 may be a battery-powered,reduced-pressure generator. This facilitates application in theoperating room and provides mobility and convenience for the patientduring the rehabilitation phase. Other sources of reduced pressure maybe utilized, such as V.A.C.® therapy unit, which is available from KCIof San Antonio, Tex., wall suction, or a mechanical unit.

The reduced pressure developed by the reduced-pressure source 120 isdelivered through the reduced-pressure delivery conduit 116, or medicalconduit or tubing, to the reduced pressure connector 114. An interposedhydrophobic membrane filter may be interspersed between thereduced-pressure delivery conduit 116 and the reduced-pressure source120. In another illustrative, non-limiting embodiment (not shown), thereduced-pressure source may be contained within the re-epithelializationdressing 102 and may be, for example, a micro-pump.

Referring now primarily to FIGS. 1 and 2, the re-epithelializationdressing 102 may include a plurality of layers or materials. Forexample, the re-epithelialization dressing 102 may include a moisttissue-interface layer 126, a support layer 128, a manifold member 130,and a sealing member 132. The sealing member 132 may be formed with aconnector aperture 134 through which at least a portion of thereduced-pressure connector 114 extends. In the illustrative,non-limiting embodiment of FIG. 1, the reduced-pressure connector 114 isshown disposed in part between the sealing member 132 and the manifoldmember 130 and with a portion extending through the connector aperture134. The re-epithelialization dressing 102 may have additional layers orfewer layers and the layers may be placed in differing combinations insome embodiments.

The moist tissue-interface layer 126 has a first side 136 and a second,tissue-facing side 138. The moist tissue-interface layer 126 is formedwith a first plurality of apertures 140, which may take any shape. Thefirst plurality of apertures 140 extend through the moisttissue-interface layer 126. The first plurality of apertures 140 may beformed with a laser, punched, drilled, or formed by casting, or anyother technique. The first plurality of apertures 140 may be formed witha uniform pattern or may be random and may have uniform or varieddiameters.

In one illustrative, non-limiting embodiment, the first plurality ofapertures 140 are formed with a uniform pattern with aperture centers141 being formed with a distance 142 between adjacent aperture centers141. In some illustrative, non-limiting embodiments, the distance 142 isabout two millimeters, three millimeters, four millimeters, fivemillimeters, six millimeters, seven millimeters, eight millimeters, ninemillimeters, ten millimeters, or more. The distance 142 may be selectedfor the desired liquid transmission through the moist tissue-interfacelayer 126. The diameter of the first plurality of apertures 140 may alsobe selected so that when reduced pressure is applied and saturationoccurs (at least in some embodiments), the first plurality of apertures140 will not firmly collapse and seal but will become restricted toallow liquid to pass but to generally restrict the passing of gasesthrough the first plurality of apertures 140. In other embodiments, thefirst plurality of apertures 140 may be sized to allow the firstplurality of apertures 140 to close completely and firmly under theinfluence of reduced pressure.

The moist tissue-interface layer 126 may be made from numerousmaterials. The moist tissue-interface layer 126 may be, for example, awater-based material, such as a hydrogel or hydrocolloid. The materialfrom which the moist tissue-interface layer 126 is formed provides afluid balance, or equilibrium, with respect to a desired moistcondition. Thus, for example, the material may provide moisture whenneeded (i.e., the tissue site 104 is dry) and will absorb moisture whenneeded (i.e., excessive moisture exists at the tissue site 104 or thetissue site 104 is substantially wet). The second, tissue-facing side138 may be a relatively smooth surface as compared to a micro-straininducing material, such as an open-cell foam. The relatively smoothsurface of the second, tissue-facing side 138 helps to promote (or atleast not hinder) cell migration. The relatively smooth surface of thesecond, tissue-facing side 138 may create little or no localmicro-strain. The moist environment provided by the moisttissue-interface layer 126, fluid management of the first plurality ofapertures 140, and the relatively smooth surface of the second,tissue-facing side 138 may encourage re-epithelialization of the wound106.

In other illustrative, non-limiting embodiments, other materials may beused for the moist tissue-interface layer 126, such as a very densehydrophilic foam (e.g., a hydrophilic closed cell foam); a film-coated,perforated, non-woven material; a hydrogel-impregnated foam; ahydroactive dressing material, or other material. Thehydrogel-impregnated foam may be particularly well suited for deeperwounds or difficult shapes. The moist tissue-interface layer 126 may beperforated or cut into sections that allow removal of one or moreportions of the moist tissue-interface layer 126 in order to providereduced pressure to a portion or the tissue site 104. An opening createdby the removed section may help with a highly exudating wound or maypromote granulation if desired in an area of the wound 106.

In use, the moist tissue-interface layer 126 will typically swell as themoist tissue interface layer 126 receives fluid under reduced pressure.With sufficient fluid, the moist tissue-interface layer 126 may becomesaturated. As shown in FIG. 3, the first plurality of apertures 140 maysubstantially swell to a restricted position, or state, as compared tothe open position, or state, of FIG. 2. The restricted position occurswhen the moist tissue-interface layer 126 is substantially saturated. Inthe restricted position, the first plurality of apertures 140 will allowliquid to pass from the tissue site 104 through the first plurality ofapertures 140 but will not substantially communicate reduced pressurethrough the first plurality of apertures 140. Other portions of there-epithelialization dressing 102 will remove fluid from the first side136 of the moist tissue-interface layer 126 once the moisttissue-interface layer 126 becomes saturated or substantially saturated.Some liquids or moisture, e.g., exudates, will remain at the wound 106and may possibly assist in the healing process by providing signals.

The re-epithelialization dressing 102 may include an optional supportlayer 128. The support layer 128 has a first side 144 and a second,tissue-facing side 146. The second, tissue-facing side 146 is disposedadjacent to the first side 136 of the moist tissue-interface layer 126.The moist tissue-interface layer 126 and the support layer 128 may becoupled. As used herein, the term “coupled” includes coupling via aseparate object and includes direct coupling. The term “coupled” alsoencompasses two or more components that are continuous with one anotherby virtue of each of the components being formed from the same piece ofmaterial. Also, the term “coupled” may include chemical, such as via achemical bond, mechanical, thermal, or electrical coupling. The term“coupled” may include any known technique, including, withoutlimitation, welding (e.g., ultrasonic or RF welding), bonding,adhesives, cements, or other techniques or devices. Fluid coupling meansthat fluid is in communication between the designated parts orlocations.

The support layer 128 is optional but may be added to provide supportfor the moist tissue-interface layer 126. As shown best by comparingFIGS. 2 and 3, the support layer 128 may help hold a first end 148 ofthe first plurality of apertures 140 in an open position or with a setdiameter while other portions may be further restricted as part of therestricted state. The support layer 128 may be formed from numerousmaterials, such as an occlusive film material. The support layer 128 maybe, for example, a polyurethane layer, a polyethylene layer, or othersupport material. The support layer 128 may help direct fluid flow andprovide support, particularly for the first plurality of apertures 140,as previously mentioned. The support layer 128 may be formed with asecond plurality of apertures 150. The second plurality of apertures 150may align and correspond with the first plurality of apertures 140. Thesecond plurality of apertures 150 may be formed in the same or similarmanner as the first plurality of apertures 140.

The re-epithelialization dressing 102 includes the manifold member 130.The manifold member 130 has a first side 152 and a second, tissue-facingside 154. The manifold member 130 may be formed from any material thatdistributes fluids, including reduced pressure. The term “manifold” asused herein generally refers to a substance or structure that isprovided to assist in applying reduced pressure to, delivering fluidsto, or removing fluids from a tissue site 104. The manifold member 130typically includes a plurality of flow channels or pathways thatdistribute fluids provided to and removed from the tissue site 104around the manifold member 130. In one illustrative, non-limitingembodiment, the flow channels or pathways are interconnected to improvedistribution of fluids provided or removed from the tissue site 104.

The manifold member 130 may include, for example, without limitation,devices that have structural elements arranged to form flow channels,such as, for example, cellular foam, open-cell foam, porous tissuecollections, liquids, gels, and foams that include, or cure to include,flow channels. The manifold member 130 may be porous and may be madefrom foam, gauze, felted mat, or any other material suited to aparticular biological application. In one illustrative, non-limitingembodiment, the manifold member 130 is a porous foam and includes aplurality of interconnected cells or pores that act as flow channels.The porous foam may be a polyurethane, open-cell, reticulated foam, suchas GranuFoam® material manufactured by Kinetic Concepts, Incorporated ofSan Antonio, Tex. Other embodiments may include “closed cells.” In onenon-limiting illustration, a manifold member 130 is formed of anon-woven material, such as a non-woven material available from LibeltexBVBA of Belgium. The second, tissue-facing side 154 of the manifoldmember 130 is disposed adjacent to the first side 144 of the supportlayer 128 in one illustrative, non-limiting embodiment or adjacent tothe first side 136 of the moist tissue-interface layer 126 in anotherillustrative, non-limiting embodiment.

The re-epithelialization dressing 102 includes the sealing member 132.The sealing member 132 has a first side 158 and a second, tissue-facingside 160. The sealing member 132 forms a sealed space over the tissuesite 104 or wound 106. The second, tissue-facing side 160 is disposedadjacent to and may be coupled to the first side 152 of the manifoldmember 130 or another layer. The sealing member 132 may be formed fromany material that provides a fluid seal. “Fluid seal,” or “seal,” meansa seal adequate to maintain reduced pressure at a desired site given theparticular reduced-pressure source or subsystem involved. The sealingmember may, for example, be an impermeable or semi-permeable,elastomeric material. “Elastomeric” means having the properties of anelastomer. Elastomeric generally refers to a polymeric material that hasrubber-like properties. More specifically, most elastomers have ultimateelongations greater than 100% and a significant amount of resilience.The resilience of a material refers to the material's ability to recoverfrom an elastic deformation. Examples of elastomers may include, but arenot limited to, natural rubbers, polyisoprene, styrene butadiene rubber,chloroprene rubber, polybutadiene, nitrile rubber, butyl rubber,ethylene propylene rubber, ethylene propylene diene monomer,chlorosulfonated polyethylene, polysulfide rubber, polyurethane, EVAfilm, co-polyester, and silicones. Additional examples of sealing membermaterials include a silicone drape, 3M Tegaderm® drape, acrylic drape,such as one available from Avery Dennison, or an incise drape.

Referring now primarily to FIG. 4, the re-epithelialization dressing 102may have an optional absorbent layer 162, or absorber, disposed betweenthe sealing member 132 and the manifold member 130 or other layers. Theabsorbent layer 162 has a first side 164 and a second, tissue-facingside 166. The first side 164 may be coupled to the second, tissue-facingside 160 of the sealing member 132 and the second, tissue-facing side166 of the absorbent layer 162 may be coupled to the first side 152 ofthe manifold member 130. The absorbent layer 162 functions primarily tostore or maintain fluids. The absorbent layer 162 may be formed fromsuper-absorbent polymers (SAP) or other materials suited for retainingfluids within the re-epithelialization dressing 102. The material andthickness of the material forming the absorbent layer 162 may beselected based on the desired quantity of fluid to be retained. Theabsorbent layer 162 may be formed from one or more constituent layers.

In operation, according to an illustrative, non-limiting embodiment, thetissue site 104, and in particular the wound 106, may be treated withthe wound treatment system 100 by deploying the re-epithelializationdressing 102. The re-epithelialization dressing 102 is placed adjacentto the wound 106 and a portion of the patient's intact epidermis 108. Ifnot already installed, the reduced-pressure connector 114 is fluidlycoupled to the re-epithelialization dressing 102 to provide reducedpressure and, if not already deployed, the sealing member 132 isdeployed over other portions of the re-epithelialization dressing 102.The second, tissue-facing side 138 of the moist tissue-interface layer126 is thus disposed adjacent to the wound 106 and a portion of theintact epidermis 108 as shown in FIG. 1. The second, tissue-facing side138 presents a moist, smooth surface to the wound 106 and the woundedges 112.

If not already installed, the reduced-pressure delivery conduit 116 isfluidly coupled to the reduced-pressure connector 114 and to thereduced-pressure source 120. The reduced-pressure source 120 isactivated and reduced pressure is thereby supplied to there-epithelialization dressing 102. The reduced pressure may help to holdthe re-epithelialization dressing 102 in situ, may help avoid any fluidleaks from the re-epithelialization dressing 102, may help avoidinfection, and may help to manage fluids.

Typically, the reduced pressure provided to the re-epithelializationdressing 102 is in the range of −10 to −100 mm Hg and more typically inthe range of −25 to −75 mm Hg. The reduced pressure is adequate to causea flow of fluid, but is not typically high enough to cause substantialmicro-strain at the tissue site 104. In other illustrative, non-limitingembodiments, the reduced pressure may be between the range of −10 mm Hgand −200 mm Hg. In other illustrative, non-limiting embodiment, thereduced pressure may be in the range of −100 to −200 mm Hg for aninitial time period and then be in the range of −25 to −100 mm Hg for asecond time period. Other variations are possible as desired.

When reduced pressure is provided to the re-epithelialization dressing102, the first plurality of apertures 140 may go immediately or overtime with saturation from an open position (FIG. 2) to a restrictedposition or state (FIG. 3). In the restricted state, the first pluralityof apertures 140 may allow liquids to pass, but prevent or restrictgases (and gaseous pressure) from being transmitted. There-epithelialization dressing 102 may thereby exert a force on thetissue site 104 without communicating gaseous pressure. If included, thesupport layer 128 may hold the first end 148 of the first plurality ofapertures 140 substantially open or with a constant diameter.

The reduced pressure delivered to the re-epithelialization dressing 102helps to remove excess fluids from the tissue site 104 and helps toremove fluids from the moist tissue-interface layer 126 when the moisttissue-interface layer 126 becomes substantially saturated. The fluidbalance, or equilibrium, of the moist tissue-interface layer 126 alsohelps manage fluid in that the moist tissue-interface layer 126 providesfluid when the tissue site 104 is dry or helps absorb fluids when thetissue site 104 is wet. The fluid removal by the moist tissue-interfacelayer 126 may be slowly accomplished to allow some exudate (but notpooling of exudate) to remain at the tissue site 104 to facilitate thehealing process. The exudate may help by allowing signaling (e.g., fromgrowth factors) to activate keratinocytes as previously mentioned.

The moist tissue-interface layer 126 also provides a relatively smoothsurface against the tissue site 104 that may facilitate (or at least notinhibit) cell migration. In addition to providing a relatively smoothmoist surface, the moist tissue-interface layer 126 may be left forextended periods of time against the tissue site 104 without granulationin-growth, infection, or the need for frequent dressing changes.

Although the present invention and its advantages have been disclosed inthe context of certain illustrative, non-limiting embodiments, it shouldbe understood that various changes, substitutions, permutations, andalterations can be made without departing from the scope of theinvention as defined by the appended claims. It will be appreciated thatany feature that is described in connection to any one embodiment mayalso be applicable to any other embodiment.

We claim:
 1. A re-epithelialization dressing for use with reducedpressure to treat a wound site, the dressing comprising: a moisttissue-interface layer for disposing adjacent to the wound site, themoist tissue-interface layer providing a moisture balance, the moisttissue-interface layer comprising a hydrogel and having a first side anda second, tissue-facing side, wherein the hydrogel has a plurality ofapertures, wherein each of the apertures extend between the first sideand the second, tissue-facing side of the hydrogel, wherein theapertures of the hydrogel are configured to substantially swell to arestricted position under the influence of increasing moisture, andwherein the second, tissue-facing side of the moist tissue-interfacelayer is smooth and adapted to substantially preclude micro-strain atthe wound site; a manifold member for distributing reduced pressure, themanifold member comprising a reticulated open-cell foam having a firstside and a second, tissue-facing side; a sealing member, the sealingmember having a first side and a second, tissue-facing side; and whereinthe manifold member is disposed between the sealing member and the moisttissue interface layer and wherein the reduced pressure is between about−25 mm Hg and −75 mm Hg and adapted to substantially precludemicro-strain at the wound.
 2. The re-epithelialization dressing of claim1, wherein the plurality of apertures of the hydrogel are moveable froman open position to the restricted position, and wherein, in therestricted position, the plurality of apertures of the hydrogel allowsliquid to pass and restricts gas from passing.
 3. There-epithelialization dressing of claim 1, wherein the moisttissue-interface layer is a hydrogel layer.
 4. The re-epithelializationdressing of claim 1, wherein the moist tissue-interface layer is a foamlayer impregnated with the hydrogel.
 5. The re-epithelializationdressing of claim 1, further comprising a support layer having a firstside and a second-tissue facing side, wherein the second-tissue facingside of the support layer is disposed adjacent to the first side of themoist tissue-interface layer and between the manifold member and themoist tissue-interface layer, the support layer having a plurality ofapertures, each of the apertures of the support layer substantiallycorresponding to one of the apertures of the hydrogel, wherein thesupport layer is coupled to the moist tissue-interface layer and adaptedto hold an end of at least one of the plurality of apertures of thehydrogel in an open position, and wherein the support layer is comprisedof an occlusive film material.
 6. The re-epithelialization dressing ofclaim 1, further comprising an absorbent layer disposed between themanifold member and the sealing member.
 7. The re-epithelializationdressing of claim 1, wherein the second, tissue-facing side of the moisttissue-interface layer is disposed adjacent to the wound site; whereinthe second, tissue-facing side of the manifold is disposed adjacent tothe first side of the moist tissue-interface layer; wherein the second,tissue-facing side of the sealing member is disposed adjacent to thefirst side of the manifold member; and wherein the plurality ofapertures in the moist tissue-interface layer are spaced by at least onemillimeter between centers.
 8. A system for promotingre-epithelialization of a wound, the system comprising: are-epithelialization wound dressing comprising: a moist tissue-interfacelayer for disposing adjacent to the wound and operable to provide amoisture balance, the moist tissue-interface layer comprising a hydrogeland having a first side and a second, tissue-facing side, wherein thehydrogel has a plurality of apertures, and wherein each of the aperturesextend between the first side and the second, tissue-facing side of thehydrogel, a manifold member for distributing reduced pressure, themanifold member comprising a reticulated open-cell foam having a firstside and a second, tissue-facing side, wherein the reduced pressure isbetween about −25 mm Hg and −75 mm Hg and adapted to substantiallypreclude micro-strain at the wound, a support layer coupled to the moisttissue-interface layer between the moist tissue-interface layer and themanifold member, the support layer adapted to hold a first end of theplurality of apertures of the hydrogel in an open position, a sealingmember, the sealing member having a first side and a second,tissue-facing side, and wherein the manifold member is disposed betweenthe sealing member and the moist tissue-interface layer; and areduced-pressure source fluidly coupled to the manifold member andwherein the second, tissue-facing side of the moist tissue-interfacelayer is smooth and adapted to substantially preclude micro-strain atthe wound site.
 9. The system of claim 8, wherein the plurality ofapertures of the hydrogel are operable, under the influence ofincreasing moisture, to substantially swell from an open position to arestricted position, and wherein, in the restricted position, theplurality of apertures of the hydrogel allows liquid to pass andrestricts gas from passing.
 10. The system of claim 8, wherein the moisttissue-interface layer is a hydrogel layer.
 11. The system of claim 8,wherein the moist tissue-interface layer is a foam layer impregnatedwith the hydrogel.
 12. The system of claim 8, wherein the support layerhas a first side and a second-tissue facing side, wherein the second,tissue-facing side of the support layer is disposed adjacent to thefirst side of the moist tissue-interface layer, wherein the supportlayer has a plurality of apertures, each of the apertures of the supportlayer substantially corresponding to one of the apertures of thehydrogel, and wherein the support layer is comprised of an occlusivefilm material.
 13. The system of claim 8, further comprising anabsorbent layer disposed between the manifold member and the sealingmember.